The Iran-backed Houthi movement claims to have seized a "spy network", after aid workers, including eleven UN employees, were kidnapped last week.
"An American-Israeli spy network was caught", the movement states in a statement, without providing any evidence to support the allegations.
It adds that those arrested were working "under the cover of international organisations and UN agencies".
The internationally recognised government of Yemen announced on Friday that the Houthi movement, among other things, attacked the office of the UN envoy to the country, Hans Grundberg, on Thursday. The Swedish Foreign Ministry announced last week that, according to the ministry's information, Hans Grundberg was not in the country at the time.
